CHEMISTRY OF FLUORESCING URANYL SALTS. 227 



ZINC URANYL ACETATE. 

 Zn (U0 2 (C 2 H 3 2 ) 3 ) 2 7H 2 0. 



This sal was prepared by Weselsky 1 and examined by Grailich. 2 Rammels- 

 berg found the axial ratio to be 0.8749 : 1 : 0.9493 in the rhombic system. 

 Grailich and Lang 3 found negative double refraction with the axes in c (001), 

 bisectrix 6. The color, according to Grailich, is yellow with weak pleochroism; 

 fluorescence is faint greenish. This salt from zinc oxide, acetic acid, and 

 uranyl acetate crystallized after some trouble in rhombic plates with little 

 fluorescence. The uranyl acetate sometimes separated without the formation 

 of the double salt. This belongs to the isomorphous magnesium group. 



CADMIUM URANYL ACETATE. 

 Cd.UO 2 .(C 2 H 3 O 2 ) 4 6H 2 O. 



These crystals were made by Weselsky 4 and examined by Grailich, who 

 found an axial ratio of 0.6289 : 1 : 0.3904 in the rhombic system. These 

 crystals were also analyzed by Rammelsberg, 5 who found that the composition 

 did not correspond to that of the zinc salt, but had a 1 to 1 ratio of bivalent 

 cadmium to uranium, thus making it like manganese and lead. These crystals 

 could not be prepared, nothing but the uranyl acetate spectra being obtained. 



MANGANESE URANYL ACETATE. 

 MnUO 2 (C 2 H 3 O 2 ) 4 6H 2 O. 



These crystals, prepared by Weselsky 6 and examined by Grailich, 7 were 

 found to have the axial ratio of 0.6330 : 1 : 0.3942 in the rhombic system by 

 Rammelsberg. The optical properties, according to Lang, are double re- 

 fraction, negative, plane of the axes a (100), bisectric c, 2E = 31, with a 

 yellow color. When prepared by evaporation of an acetic-acid solution of 

 manganese carbonate and uranyl acetate, small yellow crystals were obtained. 



Mn [(U0 2 ) (C 2 H 3 O 2 ) 3 ] 2 12H 2 O. 



These efflorescing crystals, obtained by Rammelsberg 8 from the 1 : 1 solu- 

 tion of the acetates while warm, which solution later deposited the other 

 hydrate, is isomorphous with the magnesium dodecahydrate. Rammelsberg 

 found it to be of the rhombic system, with the axial ratio of 0.7536:1:0.4957. 



LEAD URANYL ACETATE. 

 PbU0 2 (C 2 H 3 O 2 ) 4 4H 2 O. 



This salt was obtained by Wertheim 9 and later by Rammelsberg, 10 who gave 

 it the above formula, which puts it in the 1 : 1 class with cadmium and man- 

 ganese. The crystals are very readily formed as needles of any length the 

 greater the supersaturation the longer the needles. Some fairly compact 

 plates were obtained as a second crop from a highly supersaturated solution. 

 These were made from lead acetate and uranyl acetate in weighed proportions. 



TRIPLE ACETATES. 



These salts were discovered by Rammelsberg 11 in an attempt to get a copper 

 uranyl double acetate and are found when sodium acetate is present with the 

 bivalent metals, magnesium, manganese, iron, nickel, cobalt, copper, zinc, 



1 Weselsky, . lc., 58. 6 Rammelsberg, 1. c., 887. Wertheim, I. c., 227. 



2 Grailich, 1. c., 171. 6 Weselsky, I. c., 59. l Rammelsberg, Wied. Ann., 314. 



3 Lang, 1. c., 51. 7 Grailich, I. c., 175. n Ibid., 315. 



4 Weselsky, 1. c.,61. 8 Rammelsberg, I. c., 872. 



